The fasting diets Dr Michael Mosley was best known for

He changed the industry

Known as the face of intermittent fasting, Dr Michael Mosley spent decades making science and medicine more accessible to the everyday person. Here’s why the world will remember Dr Mosley’s positive impact on the health industry and ‘diet culture’.  

This week the world mourns one of the health industry's most beloved members, Dr Michael Mosley. 

Known across the world for popularising the health benefits of intermittent fasting, Dr Mosley happened upon the divisive health trend after being diagnosed with type 2 diabetes in 2012.

Enlisting the expertise and scientific research of some of the UK’s top minds, Dr Mosley set out to prove the power of intermittent fasting – not only as a way to manage his diabetes diagnosis but as an effective weight loss method.

And prove it he did.

Whether you’re familiar with his name or not, Dr Mosley’s impact on the diet and weight loss industries is undeniable. 

A regular on the BBC, appearing on science and health programs for the past few decades, the doctor-turned-tv personality shared his health journey with millions of viewers. 

Publishing The Fast Diet in 2013 with author Mimi Spencer, Dr Mosley’s book became an instant bestseller, catapulting the 5:2 diet into the global spotlight. The dieting theory was refined even further in 2018, with Dr Mosley publishing The Fast 800, a weight loss-focused approach to sustained fasting. 

Both the 5:2 diet and the Fast 800 were designed to empower people with the tools and knowledge required to achieve a long-term health transformation, not just to drop a quick few kilos. So, how exactly do the diets Dr Mosley so publicly praised work?

A little bit of planning is required ahead of fast days. Image: Getty

The 5:2 diet

The leading method in the intermittent fasting field, the 5:2 diet was designed to encourage gradual weight loss and to improve an individual’s metabolic health.

Given the spaced-out structure and flexibility of the diet, many find the method far easier to stick to in the long term than alternative diets focussed on calorie restriction. 

As the name suggests, the diet allows routine eating for five days of the week, while the remaining two are restricted to 500 to 600 calories per day. Since the two fasting days carry most of the load when it comes to retraining the metabolism, there are no strict guidelines around what you can or cannot eat during the five routine days. 

The fasting days are also entirely up to the individual – as long as they aren't consecutive – making the 5:2 diet’s flexibility far easier to incorporate into any lifestyle or routine.

Most people who regularly engage in the 5:2 method find a little bit of planning is required to ensure the fast days don’t leave them feeling entirely depleted. With the fast days’ calorie intake limited to 500 calories for women and 600 calories for men, it is recommended people opt for small meals that are high in fibre and protein. 

Lastly, sticking to the strict calorie intake on the two fast days is unlikely to be beneficial if you spend the remaining five days bingeing on junk food and highly processed, calorie-dense meals. 

Even a few healthy changes can be beneficial. Image: Pexels

The Fast 800 

Taking the methodology a step further, Dr Mosley popularised the Fast 800 method as a continuation of the 5:2 diet. Following the principles of a low-carb Mediterranean-style diet, the Fast 800 was designed to kickstart significant weight loss and reset one’s metabolism. 

Like the 5:2 method, the crux of this weight loss technique is in the name. Participants are instructed to consume only 800 calories per day for a minimum of two and a maximum of 12 weeks. To completely experience the weight loss benefits of this sustained fasting method, regular exercise is encouraged, as well as incorporating time-restricted eating. 

As we know, if we eat more calories than we burn off through exercise each day, the excess is stored as fat. The Fast 800 diet uses prolonged fasting and lowered intake of carbohydrates to encourage the body to take fat from your fat stores to burn as fuel. 

Dr Mosley famously presented a series in 2021 called Lose a Stone in 21 Days, in which individuals dropped up to 6.4kg in only three weeks using the Fast 800 method. 

At their core, the 5:2 and Fast 800 diets were designed to promote an all-round healthier lifestyle, with Dr Mosley himself demonstrating the benefits. For individuals who have struggled with disordered eating in the past, suffer from type 1 diabetes or another active medical condition, or are pregnant or breastfeeding, these fasting methods are not recommended. 

Of course, with any fasting or intermittent fasting method, it is always important to consult your healthcare professional before embarking on a new diet to ensure any medical concerns and nutritional benchmarks are able to be met. 

Originally published as The fasting diets Dr Michael Mosley was best known for